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The Connection Between GIST and KIT Protein

Medically reviewed by Elaine K. Luo, MD on February 23, 2017 — Written by Faith Black

If you’ve received a gastrointestinal stromal tumor (GIST) diagnosis, your doctor may use words like “genes,” “mutations,” “proteins,” and “cells.” Though these words are scientific, it’s important to recognize and understand the basic principles behind them. This will help you better understand the cancer.

What are genes and gene mutations?

Our genes are the blueprints and instructions that tell our body how to grow, develop, and function on a daily basis. Each cell in our body has a copy of all of these instructions. But each cell only uses the part of the instructions that are specific to their function.

Our genes are made up of proteins that are designated by the first letter of their names. These letters form their own four-letter alphabet. Sometimes, the letters get mixed up and the “words” they’re supposed to form get misspelled. This process is called a gene or genetic mutation.

A mutation causes a disease when it creates a protein that doesn’t work right or harms the body. Mutations can also cause cells to divide and grow without any regulation.

Some people are born with a germline mutation. This type of mutation can cause a disease or increase the chance of developing a disease. Other mutations are random and can happen in any cell as it’s dividing at any point in someone’s life. These are called somatic mutations. Most germline and somatic mutations can’t be avoided. However, you can control certain risk factors for particular diseases, such as smoking and lung cancer.

What is the KIT gene?

The KIT gene instructs cells to make a protein that belongs to a family called receptor tyrosine kinases. These receptors are responsible for transmitting signals from the surface of a cell to the inside of it.

The KIT protein is found in the membrane or casing of the cell. It binds or attaches to a specific protein called stem cell factor. When stem cell factor binds to the KIT protein, it turns the KIT protein on. This causes a chain of events inside the cell by turning on different groups of proteins. The proteins that are turned on by this chain of events control many different processes within the cell, including cell movement, growth, and division.

The KIT protein is only found in certain cell types, and is important for the development of these cells. Cells that use the KIT protein include:

immune cells

reproductive cells

young blood cells

nerve cells of the digestive system

The nerve cells of the digestive system are called the interstitial cells of Cajal (ICCs). These are the cells that can form GISTs.

How are KIT genes and GISTs connected?

When the KIT gene is working normally, it makes a normal protein. However, when the KIT gene gets a mutation, it can cause the protein to not work properly.

When the KIT protein isn’t working as it should, it can cause problems in any of the cellular processes. One of these problems is unregulated cell division and growth, also known as cancer.

About 80 percent of GISTs have a mutation in the KIT gene. These mutations make a protein that doesn’t require the binding of the stem cell factor to turn on the proteins involved in cellular processes. Because of this, the KIT protein and the pathways it’s responsible for remain turned on at all times. This leads to an increased rate of cell growth of the ICCs and causes GIST formation.

Researchers now understand that there’s a strong connection between KIT gene mutations and the formation of GIST tumors. As a result, they’re looking at this link and trying to create treatments that stop the development of this cancer-causing gene.

Medically reviewed by Elaine K. Luo, MD on February 23, 2017 — Written by Faith Black